Process oil, high-viscosity base oil, and process for the production thereof

Abstract

A novel process for the production of an extract useful as a process oil and a raffinate useful as a high-viscosity base oil by solvent refining is provided, characterized in that reduced pressure distillation is effected under the condition that the end point of distillate is 580° C. or higher as calculated in terms of atmospheric pressure or the initial boiling point of the residue is 450° C. or higher as calculated in terms of atmospheric pressure, the resulting residual oil is deasphalted under the condition that the carbon residue content in the deasphalted oil reached 1.6% or less, and the resulting deasphalted oil is subjected to solvent refining under the condition that the yield of extract is from 35% to 60%. It is a novel and economically excellent process for the preparation of a rubber process oil having a high safety, a high penetrating power with respect to rubber polymer and the content of PCA extract of less than 3%.

What is claimed is:  
     
         1 . A process for the production of an extract useful as a process oil and a raffinate useful as a high-viscosity base oil by solvent refining, which comprises 
 carrying out reduced pressure distillation under the condition that the end point of distillate as converted to the value under atmospheric pressure is 580° C. or higher or the initial boiling point of the residue is 450° C. or higher as calculated in terms of atmospheric pressure,    deasphalating the resulting residual oil under the condition that the carbon residue content in the deasphalted oil reaches 1.6% or less, and subjecting the resulting deasphalted oil to solvent refining under the condition that the yield of extract is from 35% to 60%.    
     
     
         2 . The production process according to    claim 1   , wherein said extract useful as a process oil exhibits a 100° C. dynamic viscosity of from 50 to 100 mm 2 /s, a percent C A  of from 15% to 35%, the content of PCA extract (IP346) of less than 3%, an aniline point of 90° C. or lower, a chromatographically-determined aromatic content of from 60% to 95% by weight and Mw (weight-average molecular weight) of 650 or more.  
     
     
         3 . The production process according to    claim 1   , wherein the high-viscosity base oil having a 40° C. dynamic viscosity of from not lower than 400 mm 2 /s to not higher than 700 mm 2 /s obtained after the dewaxing of raffinate exhibits a pour point of not higher than −5° C. and a viscosity index of not lower than 95.  
     
     
         4 . A process oil having a 100° C. dynamic viscosity of from 50 to 100 mm 2 /s, a percent C A  of from 15% to 35%, the content of PCA extract (IP346) of less than 3%, an aniline point of 90° C. or lower, a chromatographically-determined aromatic content of from 60% to 95% by weight and Mw (weight-average molecular weight) of 650 or more.  
     
     
         5 . The process oil according to    claim 4   , which has a mutagenicity index MI of less than 1.